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Background: The respiratory symptoms in welding workers have been appeare by increasing use of welding various poisoning gases and fumes in machine industry. It is necessary to evaluating of frequency of respiratory symptoms with scientific methods. Methods and Materials: In this historical cohort study, 60 non-smoker welding workers with history of at least 6 months work in welding, and 60 non-smoker office workers who were not expoused to respiratory pollution were selected from machine industry factories of Arak. Data was gathered by questionnaire. Occupationalist performed physical exams and spirometery. Data was statistically analyzed. Results: There was a significant relationship between sore throat (p=0.02), cough (p=0.04), spectrum (p=0.01), and dyspnea (p=0.007) with working in welding. But in symptoms such as rinite, hoarsening, nasal congestion, epistaxis, respiratory assessment and spirometery results difference was not significant. Conclusion: Symptoms of upper respiratory tract stimulation in welding workers were significantly more than non-expoused workers.